This invention relates generally to an ignition control circuit for an internal combustion engine and more specifically to a solid state capacitor discharge ignition unit which functions to generate an intermediate voltage during one ignition firing cycle of the system which is then discharged through the ignition coil during the next succeeding ignition firing cycle. The intermediate voltage is at a potential substantially higher than the engine's battery potential, but is also substantially less than the voltage developed across the secondary winding of the ignition coil. This intermediate voltage is of a magnitude to give sufficient firing voltage to the engine spark plugs by direct transformation of voltage levels by the ignition coil such that the coil acts essentially as a pulse transformer rather than as an inductor with transformation.
The system offers the advantage of maintaining a substantially constant transfer of energy for varying states of battery charge. Further, the use of a transistorized triggering circuit for the semiconductor switch used to discharge the stored energy through the ignition coil, provides a more positively shaped pulse for triggering, with this in turn providing a high ignition voltage to be available during cranking. Also, by providing a variable timing control for the triggering circuit, a special "retard" function is obtained that is adjustable to fit specific engine requirements.
These and other objects and advantages will become apparent to those skilled in the art upon reading the following detailed description of the accompanying drawing.